Portable sprayer with improved combination of piston and diaphragm pump

A liquid dispensing sprayer and liquid agitator for spraying insecticides, herbicides and the like including suspensions of wettable powders, comprising:

• a container adapted to be carried on the back of a person,
• a pressure vessel mounted within said container, and dual pump means connected to the container and pressure vessel for pumping liquid from said container into said pressure vessel and for agitating contents of said container, said pump means comprising:
• a piston housing section,
• a diaphragm housing section connected to one end of said piston housing section,
• a housing cover connected and sealed to said diaphragm housing section and cooperating therewith to partly define an operating pump chamber,
• a diaphragm extending across said pump chamber and having a peripheral edge captured and sealed between said cover and diaphragm housing section, said diaphragm cooperating with said diaphragm housing section to define an agitator pump chamber, and
• a piston assembly secured to said diaphragm and slidably mounted within said piston housing section, said piston assembly comprising:
• a piston body having a closed end,
• a skirt retainer fixed to said piston body and having an outer annular surface,
• a sealing skirt mounted on said outer surface of said skirt retainer, and
• resilient means interposed between said sealing skirt and said skirt retainer for urging said skirt radially outwardly of said retainer,
• valve means for connecting the interior of said piston housing section with the interior of said pressure vessel and with the interior of said container,
• a discharge tube connected with the pressure vessel for spraying liquid under pressure,
• an agitator conduit having a nozzle end in fluid communication with the interior of said container and having a pump end in fluid communication with said agitator pump chamber, and
• means for concomitantly driving said piston assembly and diaphragm, whereby liquid under pressure is pumped from the container into the pressure vessel by the piston assembly, and the diaphragm draws liquid from the container into the agitator pump chamber and projects liquid from the agitator pump chamber back into the container in a high velocity stream.